FRPI021  電子加速器  8月2日 国際科学イノベーション棟5階 ホワイエ 10:50-12:50
Impact of the transverse and longitudinal distributions of the photocathode excitation laser on the generation of THz Coherent Undulator Radiation at Kyoto University
○Siriwan Krainara, Shuya Chatani, Heishun Zen, Toshiteru Kii, Hideaki Ohgaki (IAE, Kyoto Uni.)
A THz Coherent Undulator Radiation (THz-CUR) source at Institute of Advanced Energy, Kyoto University is driven by a photocathode RF gun which generates an electron beam with the fixed energy of 4.6 MeV and the bunch charge higher than 100 pC. An intense THz-CUR is produced by injecting a short electron bunch to an undulator. Due to the low beam energy and the high charge of the electron beam, the generated electron bunch can be easily deformed by the space charge effect. This effect causes the degradation of the electron beam quality, which results in the reduction of THz-CUR intensity. The manipulation of laser distribution is one of methods to mitigate the space charge effect which can be done by changing the laser transverse profile to truncated-Gaussian and enlarging the laser pulse width before exciting the cathode. In this study, the electron bunch length at different conditions of laser distribution was examined and compared with the General Particle Tracer (GPT) simulation. The impacts of the transverse and longitudinal distributions of the laser on electron beam qualities and also the properties of THz-CUR will be presented in this paper.